In the first episode, Berry's therapist treats a patient for her fear of water by putting her under hypnosis, and then having her imagine that she's under the sea. It's all very amusing: initially he thinks she's afraid of clowns, so he's dressed up as a clown to help cure her. I liked the atmospheric music, and the fact he counted back from five to hypnotise her. A lot of therapists, including me, do use these techniques.

The key flaw lies in the way the patient in the play feels when she's under hypnosis – as if she's somehow moved outside herself. Hypnosis is more about entering into a very focused state – like when you're concentrating so hard that if someone speaks to you, it takes you a moment to reconnect.

I have treated patients for their fear of water, but I didn't do so by inviting them to imagine they were swimming alongside the Titanic. Regression therapy and past-life therapy, which I specialise in, work by asking the patient's subconscious to recall a traumatic incident that may be causing a phobia: a trapped bubble of emotion which the therapy can release. I, for instance, used to be afraid of water because I once fell into a swimming pool and was pulled under water for several minutes. I didn't need regression therapy to get over it, though — I just made myself learn to swim.

The play gives us a stereotypical view of hypnotherapists. Berry's character is rude, scary and tries to control his patients, something we just don't do. I can't say it will do much to dispel the misinformation that surrounds the industry, but it's an entertaining comedy. Luckily, I can see the funny side.

• Andrew Hillsdon is the chairman of the Past Life Therapists Association. I, Regress is on Radio 4 on Tuesdays.